Integrated thin film capacitor/inductor/interconnect system and method

ABSTRACT

A system and method for the fabrication of high reliability capacitors ( 1011 ), inductors ( 1012 ), and multi-layer interconnects ( 1013 ) (including resistors ( 1014 )) on various thin film hybrid substrate surfaces ( 0501 ) is disclosed. The disclosed method first employs a thin metal layer ( 0502 ) deposited and patterned on the substrate ( 0501 ). This thin patterned layer ( 0502 ) is used to provide both lower electrodes for capacitor structures ( 0603 ) and interconnects ( 0604 ) between upper electrode components. Next, a dielectric layer ( 0705 ) is deposited over the thin patterned layer ( 0502 ) and the dielectric layer ( 0705 ) is patterned to open contact holes ( 0806 ) to the thin patterned layer. The upper electrode layers ( 0907, 0908, 1009, 1010 ) are then deposited and patterned on top of the dielectric ( 0705 ).

CROSS REFERENCE TO RELATED APPLICATIONS UTILITY PATENT APPLICATIONS

This patent application is a divisional Patent Application for“INTEGRATED THIN FILM CAPACITOR/INTERCONNECT SYSTEM AND METHOD”, Ser.No. 09/960,796, filed Sep. 21, 2001 now U.S. Pat. No. 6,761,963.Applicants incorporate this parent application by reference and claimbenefit pursuant to 35 U.S.C. § 120 for this previously filed patentapplication.

PROVISIONAL PATENT APPLICATIONS

Applicant claims benefit pursuant to 35 U.S.C. § 119 and herebyincorporates by reference Provisional Patent Application for “INTEGRATEDTHIN FILM CAPACITOR/INTERCONNECT SYSTEM AND METHOD”, Ser. No.60/234,135, filed Sep. 21, 2000, and submitted to the USPTO with ExpressMail Label EM267139965US.

PARTIAL WAIVER OF COPYRIGHT

All of the material in this patent application is subject to copyrightprotection under the copyright laws of the United States and of othercountries. As of the first effective filing date of the presentapplication, this material is protected as unpublished material.

However, permission to copy this material is hereby granted to theextent that the copyright owner has no objection to the facsimilereproduction by anyone of the patent documentation or patent disclosure,as it appears in the United States Patent and Trademark Office patentfile or records, but otherwise reserves all copyright rights whatsoever.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable

FIELD OF THE INVENTION

The present invention provides a system and method for fabricating highreliability capacitors, inductors, and multi-layer interconnects onhybrid microelectronic substrate surfaces using thin film technology.Specifically, it employs a thin lower electrode layer under a patterneddielectric layer. Conventional thin film conductors, upper electrodesfor capacitors, spiral inductors, and resistor elements are thendeposited on top of the dielectric layer to form thin film hybridmicroelectronic devices containing conductors, capacitors, inductors,and resistors all integrated together on the same device.

BACKGROUND OF THE INVENTION

Hybrid microelectronic devices are manufactured on a variety ofsubstrate materials using various techniques such as thick film, lowtemperature co-fired ceramic (LTCC), specialty printed circuit board(PCB), or thin film technology. Hybrid devices are used in manymicroelectronics applications in the defense, medical, communications,computer, automotive, and infrared imaging industries, as well as inmany other applications. In all of these industries there is continuousdemand for devices that offer improved performance and function. Inorder to satisfy these demands, the number of passive devices(capacitors, inductors, and resistors) designed into microelectronicdevices continues to grow. For instance, a typical cellular phoneproduct may contain 400 components with less than 20 devices beingactive (i.e., semiconductors) and the 380 or more devices being passivedevices.

Along with demands for better performance are also requirements toprovide products that are less expensive and smaller in size. It isreported that the passive components in a cellular phone product canoccupy 80% of the printed circuit board area and account for 70% of theproduct assembly costs. Thus, there is clear need to reduce the size andcost of the passive devices required in microelectronic devices.

Of the hybrid circuit fabrication techniques, thin film technology isextremely well suited for use in RF/microwave, wireless, and opticaltransmission technologies because of its ability to provide high qualityfeatures, extremely dense packaging, and a large range of integratedfeatures.

The current state of the art in thin film hybrid microelectronicmanufacturing offers cost effective, high reliability methods forintegrating conductors, inductors, and resistors onto the same thin filmhybrid circuit device but not capacitors and interconnects (i.e.connections between devices and multiple layers).

Presently, capacitors are typically purchased individually and attachedto the thin film devices using various surface mount die attachtechniques. The individual chip capacitors take up valuable space,require much assembly labor, and can decrease reliability due toassembly problems.

Interconnects are often required to interconnect components and devicesand to attach to the center of spiral inductors and power splitters suchas Lange couplers. Current technology uses wire or ribbon bonding tomake individual interconnects. Wire or ribbon bonds can add higher costsand sometimes cause high frequency performance problems due to bondinconsistencies, different bond shapes or the bonds falling over andshorting to conductor lines that they are crossing over.

Thus, there is a clear need for a reliable fabrication method thatoffers both integrated capacitors and integrated interconnects. It isespecially desirable that this method provides features that are usablefrom DC to very high operating frequencies. The prior art does notsatisfy this need.

A recent approach to the integration of capacitors and interconnects hasconcentrated on fabricating these devices on silicon wafers. See MARC DESAMBER, NICK PULSFORD, MARC VAN DELDEN, ROBERT MILSOM; “Low-ComplexityMCM-D Technology with Integrated Passives for High FrequencyApplications”, The International Journal of Microcircuits and ElectronicPackaging, Volume 21, Number 2, Second Quarter 1998, pgs 224–229 (ISSN1063-1674) (International Microelectronics and Packaging Society).

This paper presented simple concepts for fabricating integratedcapacitors, inductors, resistors, and interconnects on silicon wafers.However, processing thin film hybrid substrates offers unique challengeswhen compared to silicon wafers, and the teachings presented in thisprior art are not directly applicable to thin film hybrid substrateprocessing.

DESCRIPTION OF THE PRIOR ART Overview

Two basic techniques have been used in the past to fabricate integratedcapacitors onto thin film hybrid devices. Both techniques are based onthe “parallel plate” construction or MIM (metal-insulator-metal)capacitor design. Both techniques are inherently difficult tomanufacture as they need to address the issue of “step coverage” of thedielectric layer over the thick bottom electrode.

Parallel Plate Capacitor With Step Coverage (0100)

FIG. 1 (0100) illustrates a MIM technique whereby a thin lower electrode(0102) is deposited and patterned on a substrate (0101). This lowerelectrode (0102) is then oxidized or anodized to form a thin oxide layer(0103) on its top surface that then becomes the dielectric layer in thecapacitor. An upper electrode layer (0104) is then deposited andpatterned on top of the insulator layer (0101) to form a MIM capacitor.

This type of capacitor is very difficult to manufacture as it presentsmany problems such as capacitance value reproducibility problems,shorting (0106) of the top electrode (0104) to the bottom electrode(0102) through the thin dielectric (0105), low breakdown voltage, low Q(quality factor) at high frequencies, and wire bonding challenges.

The capacitor value or capacitance is inversely proportional to thethickness of the dielectric layer so it is very advantageous to have thedielectric layer as thin as possible. When depositing a thin dielectriclayer over a thicker electrode layer electrical shorts are introduced atthe edge (0106) of the bottom electrode (0102) due to poor “stepcoverage” (0105) of the dielectric layer (0103) as shown in FIG. 1(0100).

Air-Bridge Capacitor (0200)

FIG. 2 (0200) illustrates a MIM technique that uses a thick bottomelectrode (0202), a dielectric layer (0203), and air-bridges (0204,0205, 0206) to crossover to the upper electrode layer (0207). Thistechnique uses multiple deposition and patterning processes to build upand then cross over to the upper electrode layer (0207).

This process is inherently difficult because the lower electrode (0202)is relatively thick, thereby making it problematic to make contact tothe upper electrode (0207) without shorting to the thick lower electrode(0202). Most dielectric coatings (0203), in order to be applied at athickness that will completely cover the lower electrode layer (0202),exhibit extremely low capacitance densities and therefore are used onlyrarely. Therefore, the air-bridge method becomes a logical method formaking a connection to the upper electrode (0207) because it can usethinner dielectrics with higher capacitance densities.

This method exhibits manufacturing and repeatability problems due to itsvery complex nature. It is extremely expensive and problematic toproduce. It also suffers from reliability problems because the airbridges are vulnerable to shorts from handling.

Air-Bridge Interconnects (0300)

In an effort to fabricate integrated interconnects, a “crossover” or“air-bridge” technique has also been employed, as described in FIG. 3(0300). This technique uses multiple deposition and patterning processeson a substrate (0301) to build up (0303) and then crossover (0304) thickconductor traces (0302) to form interconnects. The processes aretypically expensive and therefore can usually only be used in highvolume production or in specialty applications that are not costsensitive. Additionally, the air-bridge spans (0304) are fragile and canbe deformed or collapsed by simple handling. It is also important tonote that due to the complex nature of the air-bridge process, it isextremely rare for air-bridge interconnects and air-bridge capacitors tobe produced on the same device.

Air-Bridge Interconnects with Support (0400)

A more complex version of the simple air-bridge is to support thecrossover span (0402) with an underlying insulating material (0403), asillustrated in FIG. 4 (0400). Supported crossovers prevent the crossover span from being deformed and causing it to short to the conductorlines underneath. Usually polyimide is used as the supportinginsulation.

The addition of the insulating support (0403) under the span (0402)increases the complexity and cost of the supported crossover process. Itis again important to note that due to the complex nature of thesupported air-bridge process, it is extremely rare for supportedair-bridge interconnects and air-bridge capacitors to be produced on thesame device.

Prior U.S. Patents

The prior art in this area relates generally to the following U.S. Pat.Nos.: 3,969,197; 4,002,542; 4,002,545; 4,038,167; 4,062,749; 4,364,099;4,408,254; 4,410,867; 4,423,087; 4,471,405; 4,599,678; 4,631,633;5,122,923; 5,258,886; 5,262,920; 5,338,950; 5,390,072; 5,455,064;5,539,613; 5,587,870; 5,643,804; 5,670,408; 5,685,968; 5,693,595;5,699,224; 5,708,302; 5,736,448; 5,737,179; 5,745,335; 5,760,432;5,767,564; 5,781,081; 5,818,079; 5,872,040; 5,874,379; 5,877,533;5,882,946; 5,883,781; 5,889,299; 5,907,470; 5,912,044; 5,936,831;5,943,547; 5,973,908; 5,973,911; 5,982,018; 6,001,702; 6,023,407;6,023,408; 6,040,594; 6,069,388; 6,072,205; 6,075,691.

These patents generally address the following general areas:

-   1. Fabrication of capacitors on silicon wafers. Unfortunately, the    manufacturing techniques utilized here are inapplicable to thin film    hybrid substrate fabrication.-   2. Fabrication of capacitors on thick film hybrid substrates. While    these techniques do permit capacitor fabrication, the performance of    these devices is limited and their manufacturing yield is generally    low due to step coverage problems and/or problems with crossover    bridge spans.-   3. Fabrication of capacitors on thick film hybrid substrates using    exotic plating techniques. These systems generally have high    manufacturing costs and lower device performance than the present    invention.    None of the prior art teaches the use of very thin metalization for    the bottom plating of capacitors to avoid step coverage problems and    improve manufacturing yield.

OBJECTIVES OF THE INVENTION

The present invention provides a system and method for fabricating costeffective, high reliability capacitors and multi-layer interconnects inorder to provide the ability to integrate capacitors and interconnectsalong with conductors, inductors, and resistors all on the same thinfilm hybrid microelectronic device. Accordingly, the objectives of thepresent invention are (among others) to circumvent the deficiencies inthe prior art and affect one or more of the following:

-   1. It is an object of this present invention to provide a method for    forming capacitors and interconnects on thin film hybrid    microelectronic substrates. This method first employs a thin metal    layer deposited and patterned on the substrate. This thin patterned    layer is used to provide both lower electrodes for capacitor    structures and interconnects between upper electrode components.    Next, a dielectric layer is deposited over the thin patterned layer    and the dielectric layer is patterned to open contact holes to the    lower electrode layer. The upper electrode layers are then deposited    and patterned on top of the dielectric layer to define the    conductors, resistors, and inductors. Thus, by first depositing and    patterning the thin lower electrode layer that becomes encapsulated    by a suitable dielectric layer under the thick upper electrodes;    this invention simply and economically solves many of the problems    associated with past methodologies.-   2. According to a further object of the present invention, the lower    electrode and interconnect layer are made of a material that is    mainly gold (Au).-   3. According to a further object of the present invention, the lower    electrode and interconnect layer are made of a material that is    mainly copper (Cu).-   4. According to a further object of the present invention, the lower    electrode and interconnect layer are made of a material that is    mainly silver (Ag).-   5. According to a further object of the present invention, the lower    electrode and interconnect layer are made of a material that is    mainly aluminum (Al).-   6. According to a further object of the present invention, the lower    electrode and interconnect layer are made of one or more metals    selected from a group consisting of tantalum (Ta), tungsten (W),    titanium (Ti), nickel (Ni), molybdenum (Mo), platinum (Pt),    palladium (Pd), or chromium (Cr).-   7. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly silicon    nitride (Si₃N₄).-   8. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly silicon    dioxide (SiO₂).-   9. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly silicon    oxynitride (SiO_(X)N_(X)).-   10. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly aluminum oxide    (Al₂O₃).-   11. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly tantalum    pentoxide (Ta₂O₅).-   12. According to a further object of the present invention, the    dielectric layer is made of a material that consists of a    ferroelectric material that is mainly BaTiO₃, SrTiO₃, BaTiO₃,    PbZrO₃, PbTiO₃, LiNbO₃, or Bi₁₄Ti₃O₁₂.-   13. According to a further object of the present invention, the    dielectric layer is made of a material that is mainly polyimide or    benzocyclobutene.-   14. According to a further object of the present invention, the    substrate material is made of one or more of materials selected from    a group consisting of alumina (Al₂O₃), beryllium oxide (BeO), fused    silica (SiO₂), aluminum nitride (AlN), sapphire (Al₂O₃), ferrite,    diamond, LTCC, or glass.    While these objectives should not be understood to limit the    teachings of the present invention, in general these objectives are    achieved by the disclosed invention that is discussed in the    following sections.

BRIEF SUMMARY OF THE INVENTION

The invention is related in the general area of generating integratedthin film capacitors and other passive components along with associatedinterconnect. To date, the industry has been unable to commerciallyfabricate a viable integrated capacitor in the thin film industry. Thesystem and method described in the figures and the following textdiscloses such a system that can be fabricated using conventional thinfilm technologies at substantially reduced costs over methods currentlyused within the industry.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the advantages provided by the invention,reference should be made to the following detailed description togetherwith the accompanying drawings wherein:

FIG. 1 illustrates a prior art parallel plate capacitor structure with“step coverage” defects;

FIG. 2 illustrates a prior art air-bridge parallel plate capacitorstructure;

FIG. 3 illustrates a prior art air-bridge interconnect structure;

FIG. 4 illustrates a prior art air-bridge interconnect structureincorporating polyimide crossover span supports;

FIG. 5 illustrates a sectional view for illustration of the process forforming integrated capacitors and interconnects on a substrate (0501)according to the present invention and illustrates the step ofmetalizing (0502) the substrate (0501) with the lower electrode andinterconnect layer (0502);

FIG. 6 illustrates a view similar to FIG. 5 but illustrates a furtherstep of forming the individual lower electrodes (0603) for thecapacitors and the interconnects (0604);

FIG. 7 illustrates a view similar to FIG. 6 but illustrates a furtherstep of applying the dielectric layer (0705) on top of the patternedindividual lower electrodes and the interconnects;

FIG. 8 illustrates a view similar to FIG. 8 but illustrates a furtherstep of forming contact holes (0806) to the lower electrodes andinterconnects;

FIG. 9 illustrates a view similar to FIG. 8 but illustrates a furtherstep of metalizing the top of the dielectric layer (0705) with theconductor (0907, 0908) and optional resistor layers;

FIG. 10 illustrates a view similar to FIG. 9 but illustrates a furtherstep of patterning the conductor layer with the individual upperelectrodes (1009), capacitors (1011), spiral inductors (1012),interconnect (1013), and optional resistor elements (1014);

FIG. 11 illustrates an exemplary bypass/decoupling/filter capacitorapplication structure using the teachings of the present invention;

FIG. 12 illustrates an exemplary bypass/decoupling/filter capacitorapplication in which the teachings of the present invention areparticularly advantageous;

FIG. 13 illustrates an exemplary active element phased antenna arrayapplication using the teachings of the present invention;

FIG. 14 illustrates an exemplary process flowchart that implements afabrication method taught by the present invention;

FIG. 15 illustrates typical performance of the capacitors fabricatedusing the teachings of the present invention;

FIG. 16 illustrates typical performance of the inductors fabricatedusing the teachings of the present invention.

DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS Embodimentsare Exemplary

While this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetailed preferred embodiment of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiment illustrated.

The numerous innovative teachings of the present application will bedescribed with particular reference to the presently preferredembodiments, wherein these innovative teachings are advantageouslyapplied to the particular problems of an INTEGRATED THIN FILMCAPACITOR/INDUCTOR/INTERCONNECT SYSTEM AND METHOD. However, it should beunderstood that these embodiments are only examples of the manyadvantageous uses of the innovative teachings herein. In general,statements made in the specification of the present application do notnecessarily limit any of the various claimed inventions. Moreover, somestatements may apply to some inventive features but not to others. Ingeneral, unless otherwise indicated, singular elements may be in theplural and visa versa with no loss of generality.

System (0500, 0600, 0700, 0800, 0900, 1000)

Referring to the system as described in FIGS. 5–11 (0500, 0600, 0700,0800, 0900, 1000, 1100) and method as described in FIG. 14 (1400), asubstrate and method for forming same containing integrated capacitors,inductors and/or interconnects along with conductors and/or resistorswill now be described.

[1] Metalization (1401)

As shown in FIG. 5 (0500), a substrate (0501) is metalized (0502) on oneor both sides by sputtering, evaporation, or chemical vapor deposition(1401).

This layer (0502) is typically formed of a lower adhesive layer and anupper conducting layer. Key to the success of the present invention iskeeping the total thickness of this metalized layer (0502) at or belowapproximately 1.50 μm. The prior art universally teaches the use of basemetalization layers on the order of 2–4 μm in thickness that makes stepcoverage difficult in all known capacitor/inductor/interconnectfabrication processes. The present invention breaks with thismethodology and utilizes a much thinner adhesive/conducting layercombination to achieve reliable step coverage and superior passivecomponent performance.

The lower adhesive layer is generally very thin (˜0.03–0.05 μm) and isoptimally comprised of chrome (Cr), titanium (Ti), or titanium-tungsten(Wti), although other adhesive conducting materials are also known inthe art. The purpose of this layer is to generally act as a bondinginterface between the substrate (0501) and the conducting layer (0502).

The upper conducting layer is generally thicker (˜0.25 μm) than thelower adhesive layer and may be comprised of any of a wide variety ofmetals, but preferred embodiments utilize gold (Au), copper (Cu),aluminum (Al), silver (Ag), tantalum (Ta), tungsten (W), titanium (Ti),nickel (Ni), molybdenum (Mo), platinum (Pt), and/or palladium (Pd). Thecombination of the lower adhesive layer and upper conducting layerserves as the bottom electrode layer (0502).

[2] Align/Expose/Etch Lower Electrodes (1402)

A photoresist (not shown) is then applied, imaged, and the substrateetched (1402) to form the desired patterns for the lower electrodes ofthe capacitors (0603) and any interconnects (0604), as shown in FIG. 6(0600).

[3] Apply Dielectric Layer (1403)

Then, as shown in FIG. 7 (0700), the dielectric layer of silicon nitride(0.3 μm) (0705) is applied to the entire substrate (0501) surface bychemical vapor deposition (CVD) (1403). One skilled in the art willrecognize that other dielectric layer materials are possible. Whilesilicon nitride is a preferred dielectric, a wide variety of othermaterials are anticipated by the present invention and detailed later inthis document.

[4] Align/Expose/Etch Contact Holes (1404)

Thereafter, as shown in FIG. 8 (0800), a photoresist (not shown) is thenapplied, imaged, and the substrate is plasma etched (1404) to form thecontact holes (0806) in the dielectric layer (0705) in order to be ableto make electrical contact to the lower electrodes of the capacitors(0603) and the interconnect (0604).

Note also that in many applications it will be advantageous toselectively pattern the dielectric layer to remove certain portions ofdielectric under the upper level metalization. This optional selectivepatterning can easily be accomplished in this same step. Rationales forthis selective patterning procedure may be associated with improving theelectrical performance of variouscapacitor/inductor/interconnect/resistor components, as one skilled inthe art will readily recognize.

[5] Metalize Substrate to Make Contact With Lower Electrodes (1405)

FIG. 9 (0900) shows that the substrate is then metalized with the upperelectrode metal layers by sputtering, evaporation, chemical vapordeposition, and/or electroplating (1405). These metal layers (0907,0908) are commonly tantalum nitride (to serve as the resistor layer)under WTi (0.05 μm) (0907) under Au (2–5 μm) (0908). These metal layerscoat the entire substrate surface and make contact to the lowerelectrode and interconnect patterns through the contact holes.

[6] Align/Expose/Etch Upper Electrode/Inductor/Conductor (1406)

Thereupon, as shown in FIG. 10 (1000), photoresist (not shown) isapplied, imaged, and the substrate is etched (1406) to form theconductor layer features, upper electrode pads (1009), and optionalspiral inductors (1010). One skilled in the art will recognize that awide variety of spiral inductor geometries are possible using theteachings of the present invention, and are not limited to the specificspiral inductor illustrated (1010).

[7] Optionally Form Resistor Elements (1407)

In FIG. 10 (1000) the resistor elements (1014) are optionally formed byapplying photoresist (not shown), imaging the photoresist, and thenetching the resistor layer (1407).

Construction Variations

From the foregoing, it will be understood by one skilled in the art thataccording to the present invention a lower electrode and interconnectlayer formed using a high conductivity material such as Au, Ag, Cu, orAl will offer excellent high frequency characteristics.

It will be further understood that according to the present inventionthe dielectric material and thickness can be chosen to optimizecapacitance values and/or breakdown voltage.

It will be further understood that according to the present invention tointegrate capacitors and interconnects on a variety of thin film hybridsubstrates and surface finishes along with conductors, inductors, andresistor elements.

Summary

In summary, it will be understood by one skilled in the art thataccording to the present invention it becomes possible to integratecapacitors, inductors, and/or interconnects on a thin film hybridsubstrate along with conductors and/or resistor elements in a widevariety of configurations.

Method (1400)

As described previously, the exemplary method used to fabricate thecapacitor/inductor/interconnect of the present invention is illustratedin FIG. 14 (1400) and is summarized in the following steps:

-   1. metalize the substrate with a thin metal overcoat (1401);-   2. align/image photoresist and etching to form patterns for lower    capacitor electrodes and interconnect (1402);-   3. apply the thin dielectric layer (1403);-   4. apply/image the photoresist and etch to form contact holes    (1404);-   5. metalize substrate to make contact with lower electrodes (1405);-   6. apply/image photoresist and etch to form patterns for    conductor/inductor layer and upper electrode (1406); and-   7. optionally form resistor elements by applying/imaging photoresist    and etching resistor layer (1407).    Key to this process is the thin application of metalization in    step (1) to allow the use of a thin dielectric layer in step (2) to    minimize the impact of step coverage reliability problems that are    present in the prior art.

System/Method Variations

Material Variations

The present invention is amenable to a wide variety of system/methodvariations, some of which include the following:

-   1. The lower electrode and interconnect layer may be comprised of    materials that are mainly gold (Au), copper (Cu), silver (Ag),    aluminum (Al).-   2. The lower electrode and interconnect layer may be comprised of    materials that are made of one or more metals selected from a group    consisting of tantalum (Ta), tungsten (W), titanium (Ti), nickel    (Ni), molybdenum (Mo), platinum (Pt), palladium (Pd), or chromium    (Cr).-   3. The dielectric layer may be comprised of materials that are made    of a material that is mainly silicon nitride (Si₃N₄), silicon    dioxide (SiO₂), silicon oxynitride (SiO_(X)N_(X)), aluminum oxide    (Al₂O₃), or tantalum pentoxide (Ta₂O₅).-   4. The dielectric layer may be comprised of materials that that    consists of a ferroelectric material that is mainly BaTiO₃, SrTiO₃,    BaTiO₃, PbZrO₃, PbTiO₃, LiNbO₃, or Bi₁₄Ti₃O₁₂.-   5. The dielectric layer may be comprised of a material that is    mainly polyimide or benzocyclobutene.-   6. The substrate may be comprised of materials that are selected    from a group consisting of alumina (Al₂O₃), beryllium oxide (BeO),    fused silica (SiO₂), aluminum nitride (AlN), sapphire (Al₂O₃),    ferrite, diamond, LTCC, or glass.    Note that while these variations constitute preferred embodiments of    the present invention, they are not limitive of the teachings of the    present invention.    Bypass/Decoupling/Filter Capacitor Variant (1100)

An important variation of the exemplary system/method involves thebypass/decoupling/filter capacitor structure illustrated in FIG. 11(1100). As illustrated in FIG. 12 (1200), a large number of RF/microwaveapplications involve amplifier systems (1210) that have a need fordecoupling (1213) and/or filter (1214) capacitors that have one plategrounded.

The present invention when applied to this typical application ispresented by the exemplary construction diagram of FIG. 11 (1100). Inthis application, the substrate (1101) is generally metalized on theback surface (1102) and this back surface is grounded (1103). A contactgrounding via (1104) is drilled through the substrate (1101) andmetallized or filled to make contact with the grounded (1103)metalization (1102). This via then makes contact with the top layer ofinterconnect metalization (1113) that forms the top plate of thecapacitor structures. This forms an electrical ground connection (1114)between the upper capacitor plate metalization (1113) and the back platemetalization (1102) by means of the via contact (1104).

The capacitor structures generally comprise thinly deposited lowerplates (1105, 1106) and an overcoat of dielectric (1107, 1108). Contactto the lower plates (1105, 1106) is made with via contacts (1109, 1110)through the dielectric, which make contact with upper layers of thickmetalized interconnect (1111, 1112).

The advantage of this structure is evident when compared to the priorart because it permits the ground contact of the capacitor to be placedwithin the capacitor, thus reducing both the series resistance of thecapacitor contacts as well as the inductance normally associated withcrossover spans and other interconnect associated with techniques usedin the prior art.

It is important to note that within the context of the prior art, thelower capacitor plates (1105, 1106) would normally be formed as thickmetalization comparable to the top interconnect (1111, 1112, 1113), thusmaking step coverage of the dielectric layer (1107, 1108) problematicand unreliable. The construction technique and materials taught by thepresent invention overcome these deficiencies in the prior art andprovide for a higher degree of performance and reliability than possiblewith prior art structures.

One skilled in the art will recognize that the capacitor structuredepicted in FIG. 11 (1100) depicts two separate capacitor structureshaving two bottom plates (1105, 1106) with corresponding dielectriclayers (1107, 1108). This illustrates how a single ground contact via(1104) and top plate (1113) may be shared among proximal capacitors.This improves the area efficiency of the overall capacitor structure andpermits multiple capacitors to be paralleled forbypass/decoupling/filtering purposes. This parallelism tends to improvethe overall function of these devices in a given application, and mayalso be used to isolate power supply noise between various stages withina given active amplifier (1211) or other active element.

Product By Process

Referring to the system as described in FIGS. 5–11 (0500, 0600, 0700,0800, 0900, 1000, 1100) and method as described in FIG. 14 (1400), theresulting product containing integrated capacitors, inductors and/orinterconnects along with conductors and/or resistors will now bediscussed.

What is significant to note about the individual capacitors, inductors,and interconnect (fabricated using the method illustrated herein and forwhich an exemplary flowchart is given in FIG. 14 (1400)), is that theelectrical characteristics of these components are superior to thatpossible with the prior art. This difference in kind is possiblebecause:

-   1. The parasitic inductance associated with the capacitors formed    using the teachings of the present invention is necessarily lower    than that of the prior art. This is because the length of    interconnect required to actually connect the capacitor to the    remainder of the hybrid circuit need not use crossover spans as in    the prior art. These crossover spans tend to add parasitic    capacitance that reduces the self-resonant frequency of the    capacitor.-   2. Additionally, the parasitic resistance of the capacitor    structures is reduced as compared to the prior art because crossover    spans and additional interconnect required by the prior art has a    finite resistance which reduces the quality factor (Q) of the    capacitor structure. This parasitic resistance is well known by one    skilled in the art as “effective series resistance” and is    necessarily a degradation of device performance.-   3. The parasitic capacitance associated with the inductors and    interconnect using the teachings of the present invention is    significantly lower than that of the prior art. This is in part    because the prior art has difficulty in controlling the dielectric    thickness of the sidewalls (0105) of the upper layer conducting    layers.-   4. The present invention has significantly better reliability and    manufacturability because of the improvement in step coverage as    compared to the prior art. As illustrated in FIG. 1 (0106), the    potential for sidewall punchthrough or shorting is a significant    drawback of the prior art. This potential defect reduces    manufacturing yields, causes failures in the field, and generally    increases the final cost of the manufactured hybrid system.-   5. Note that since the reliability of a system containing multiple    capacitors, inductors, and interconnects is determined by the    weakest link in the system, an large array of hybrid components    having poor individual reliability drastically increases the cost of    the overall system because of the reduced overall system    reliability.-   6. Note that in space-constrained designs and also high performance    designs, the ability to overlap ground contact vias (1104) with an    overlapping capacitor structure increased the area efficiency and    high frequency performance of bypass/decoupling/filtering capacitor    structures. This is a significant performance improvement over the    prior art.    One skilled in the art will no doubt observe other advantages to the    present invention as compared to the prior art.

EXEMPLARY SYSTEM APPLICATIONS Overview

While a wide variety of system applications are amenable to use of thepresent invention, several are preferred and will now be discussed.Discussion of these applications in no way limits the scope of thepresent invention.

Bypass/Decoupling/Filter Systems (1200)

One application of the present invention is in bypass/decoupling/filtersystems as illustrated in FIG. 12 (1200). In this application (1200), anamplifier system (1210) is supplied by some external power supply(1220). Typically in RF/microwave applications these systems (1210)comprise an amplifier (1211) which is fed with power via an inductor(1212)/capacitor (1213) filter. In this application it is very importantthat the capacitor (1213) be placed physically close to the amplifier(1211) to minimize its inductance and raise its self-resonant frequency.

The present invention is particularly well suited to this applicationbecause it permits the inductor (1212) and capacitor (1213) to be fullyintegrated on the same substrate in close proximity to the amplifier(1211). Furthermore, the thin dielectric and low effective seriesresistance of the capacitors constructed using the techniques of thepresent invention permit the power supply bypass/decoupling/filteringoperation of the capacitor (1213) to be superior to the use of anychip-capacitor alternative. The reason for this is that anychip-capacitor alternative will have significant inductance associatedwith bond pads and bonding sidewalls of the chip-capacitor, thusreducing its effective capacitance at high frequencies.

Additionally, other capacitors (1214) and/or inductors (1215) that maybe associated with the amplifier (1211) within the context of theamplifier subsystem (1210) are also amenable to implementation using thepresent invention. Applications for these components will vary based onthe specific function of the amplifier system (1210). Note that inaddition to capacitors (1214) and inductors (1215), the presentinvention also permits integration of resistor elements in closeproximity to the amplifier (1211), which further increases theperformance and reliability of the manufactured system while reducingthe overall cost of the completed subsystem (1210).

Active/Passive Element Phased Antenna Arrays (1300)

The amplifier subsystem (1210) illustrated in FIG. 12 (1200) may bearrayed as illustrated in FIG. 13 (1300) in both the X-direction (1310)and the Y-direction (1320) to form a phased antenna array. While thearray elements (1210) of the phased antenna array (1300) are optimallyactive systems as illustrated in FIG. 12 (1200), one skilled in the artwill readily recognize that the same principles may be applied to phasedantenna arrays that are comprised primarily (or solely) of passiveinductor and/or capacitor elements.

The advantage of the present invention over the prior art in thisapplication is significant. Traditional phased antenna arrays utilizingcapacitors/inductors/interconnect generally comprise componentsfabricated using crossover spans as illustrated in FIG. 3 (0300) andFIG. 4 (0400). As mentioned previously, the crossover spans (0304) inthis technique are particularly susceptible to damage/collapse becauseof their fragile nature. The use of polyimide supports (0403) in thisapplication partially solves this problem, but does so only at theexpense of added manufacturing cost. Given that tens of thousands of thearray elements (1210) may be present in phased antenna array, thisadditional cost and reduced reliability of the prior art is asignificant hindrance to the implementation of integrated phased antennaarray structures.

Furthermore, the crossover bridge (0304) technique illustrated in FIGS.3–4 does not generate the same capacitance per unit area performance asis possible with the present invention. This is because the area of theentire crossover span structure of FIGS. 3–4 is greater than that of thepresent invention, and its effective capacitance per unit area is thusless than that of the present invention. Finally, the additionalconnection lead structures associated with the crossover span (0304)introduce additional parasitic inductance into the capacitancestructure, thus reducing its resonant frequency and making it unsuitablefor some very high frequency applications.

Thus, the present invention specifically anticipates the use of the thinfilm capacitor/inductor/interconnect structures described herein in bothactive and passive phased antenna arrays. These phased antenna arrayshave wide application as is well known to one skilled in the art.

EXEMPLARY SYSTEM COMPONENT CHARACTERISTICS Capacitor Performance (1500)

FIG. 15 (1500) illustrates typical modeled performance of capacitorsusing the teachings of the present invention. Key to interpretation ofthis graph is the fact that the capacitor structure operates below theself-resonant point (1501) with capacitive behavior (1502), but abovethis point it appears to have inductive characteristics (1503). This istypical of all hybrid capacitor structures, but the advantage in thepresent invention is that the self-resonant point (1501) is higher thancomparable prior art solutions, with lower effective series resistance.

Fabricated capacitor test structures using the teachings of the presentinvention had remarkably consistent capacitance values in the 15–30 pFrange and self-resonant frequencies ranging from 1.4–2.4 GHz, which ismore than sufficient performance for many RF/wireless applications andsignificantly better than comparable prior art capacitor structures.

Inductor Performance (1600)

FIG. 16 (1600) illustrates typical modeled performance of inductorsusing the teachings of the present invention. Key to interpretation ofthis graph is the fact that the inductor structure operates below theself-resonant point (1601) with inductive behavior (1602), but abovethis point it appears to have capacitive characteristics (1603). This istypical of all hybrid inductor structures, but the advantage in thepresent invention is that the self-resonant point (1601) and qualityfactor (Q) are higher than comparable prior art solutions, since thepresent invention inductors have lower series resistance values andtighter inductive coupling with lower parasitic capacitance.

Fabricated inductor test structures using the teachings of the presentinvention had remarkably consistent inductance values in the 20–70 nHrange and quality factors (Q) ranging from 22 at 2 GHz (20 nH) to 14 at800 MHz (70 nH). While this performance analysis is preliminary, it doesindicate that the present invention teachings permit inductors to befabricated with significantly higher reliability, manufacturability, andperformance than possible with the prior art.

CONCLUSION

A system and method for the fabrication of high reliability capacitors,inductors, and multi-layer interconnects on various substrate surfaceshas been disclosed. The disclosed method first employs a thin metallayer deposited and patterned on the substrate. This thin patternedlayer is used to provide both lower electrodes for capacitor structuresand interconnects for upper electrode components. Next, a dielectriclayer is deposited over the thin patterned layer and the dielectriclayer is patterned to open contact holes to the thin patterned layer.The upper electrode layer is then deposited and patterned on top of thedielectric.

Although a preferred embodiment of the present invention has beenillustrated in the accompanying drawings and described in the foregoingdetailed description, it will be understood that the invention is notlimited to the embodiments disclosed, but is capable of numerousrearrangements, modifications, and substitutions without departing fromthe spirit of the invention as set forth and defined by the followingclaims:

1. A thin film capacitor/inductor/interconnect method comprising: (a)thinly metalizing a substrate with a lower electrode and interconnectlayer formed on said thin film hybrid substrate, said layer furthercomprising a lower adhesive layer and an upper conducting layer having asum total thickness of less than or equal to 1.5 microns; (b)applying/imaging photoresist and etching to form metal patterns on saidsubstrate for lower capacitor electrodes and interconnect; (c) applyinga thin dielectric layer to said metal patterns; (d) applying/imagingphotoresist and etching to form contact holes in said dielectric layerand optionally selectively patterning said dielectric layer; (e)metalizing said substrate to make contact with said lower capacitorelectrodes and interconnect; (f) applying/imaging photoresist andetching to form patterns for upper capacitor electrodes, inductors,and/or interconnect conductors; (g) optionally forming resistor elementsby applying/imaging photoresist and etching a resistor layer on saidsubstrate; wherein said upper conducting layer is approximately 0.25microns thick.
 2. The thin film hybrid substrate method of claim 1,wherein said lower adhesive layer is approximately 0.03 to 0.05 micronsthick.
 3. The thin film hybrid substrate method of claim 1, wherein saidlower adhesive layer comprises chrome.
 4. The thin film hybrid substratemethod of claim 1, wherein said lower adhesive layer comprises titanium.5. The thin film hybrid substrate method of claim 1, wherein said loweradhesive layer comprises titanium-tungsten.
 6. The thin film hybridsubstrate method of claim 1, wherein said upper conducting layercomprises silver.
 7. The thin film hybrid substrate method of claim 1,wherein said upper conducting layer comprises aluminum.
 8. The thin filmhybrid substrate method of claim 1, wherein said upper conducting layercomprises gold.
 9. The thin film hybrid substrate method of claim 1,wherein said upper conducting layer comprises copper.
 10. The thin filmhybrid substrate method of claim 1, wherein said lower electrode andinterconnect layer further comprises silver.
 11. The thin film hybridsubstrate method of claim 1, wherein said lower electrode andinterconnect layer further comprises aluminum.
 12. The thin film hybridsubstrate method of claim 1, wherein said lower electrode andinterconnect layer further comprises gold.
 13. The thin film hybridsubstrate method of claim 1, wherein said lower electrode andinterconnect layer further comprises copper.
 14. The thin film hybridsubstrate method of claim 1, wherein said lower electrode andinterconnect layer is selected from the group consisting of tantalum,tungsten, titanium, nickel, molybdenum, platinum, palladium, andchromium.
 15. The thin film hybrid substrate method of claim 1, whereinsaid dielectric layer is selectively patterned.
 16. The thin film hybridsubstrate method of claim 1, wherein said dielectric layer furthercomprises silicon nitride.
 17. The thin film hybrid substrate method ofclaim 1, wherein said dielectric layer further comprises silicondioxide.
 18. The thin film hybrid substrate method of claim 1, whereinsaid dielectric layer further comprises silicon oxynitride.
 19. The thinfilm hybrid substrate method of claim 1, wherein said dielectric layerfurther comprises aluminum oxide.
 20. The thin film hybrid substratemethod of claim 1, wherein said dielectric layer further comprisestantalum pentoxide.
 21. The thin film hybrid substrate method of claim1, wherein said dielectric layer further comprises a ferroelectricmaterial.
 22. The thin film hybrid substrate method of claim 21, whereinsaid ferroelectric material is BaTiO₃.
 23. The thin film hybridsubstrate method of claim 21, wherein said ferroelectric material isSrTiO₃.
 24. The thin film hybrid substrate method of claim 21, whereinsaid ferroelectric material is PbZrO₃.
 25. The thin film hybridsubstrate method of claim 21, wherein said ferroelectric material isPbTiO₃.
 26. The thin film hybrid substrate method of claim 21, whereinsaid ferroelectric material is LiNbO₃.
 27. The thin film hybridsubstrate method of claim 21, wherein said ferroelectric material isBi₁₄Ti₃O₁₂.
 28. The thin film hybrid substrate method of claim 1,wherein said dielectric layer further comprises polyimide.
 29. The thinfilm hybrid substrate method of claim 1, wherein said dielectric layerfurther comprises benzocyclobutene.
 30. The thin film hybrid substratemethod of claim 1, wherein said substrate material is selected from thegroup consisting of alumina, beryllium oxide, fused silica, aluminumnitride, sapphire, ferrite, diamond, LTCC, and glass.